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April 6th, 2007, 06:17 AM   #1
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New valve guides + valve size

Just picked up my new valve guides, tried to get the valve in , but it doesn't fit? Could it be that the valve guides need to be pressed in the head first and then honed to the right size or did I just get the wrong guides? Part numbers match with the husa parts list.

Anyone happen to know what diameter the stock valve stems are? Als the in and outside diameter af a valve guide would be handy.

Thanks, Christof.
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April 6th, 2007, 07:21 AM   #2
oyk
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hi , long time ago had the same problem in my fe600 1994
turned out to be wrong part! somewhere in 97 they revised the valve guides along with many parts in the top end
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April 6th, 2007, 08:02 AM   #3
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Sorry forgot to mention what bike, it's a 2002 650
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April 6th, 2007, 08:59 AM   #4
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Dear Mr Bastard,
check that the end of the valve stem has no "burr". If so, gently grind the edge.
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April 6th, 2007, 09:37 AM   #5
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As valve quides are a light press fit in the cylinder head and removing them requires thermal expansion and light force from a special tool the correct head to quide fit cannot be guaranteed as there is always the chance of metal stretching and transfer if an exact copy of the original guide is used as a replacement.As such it is normal for the guide to be slightly oversize to enable the correct interference fit.
As well the inner surface of the quide(where the valve slides)cannot be machined to fit the valve as the expansion of the quide inward from the press fit installation in the head makes this difficult calculate.
Also the installation of a new valve quide often results in the valve not being in the perfect original alignment with the valve seat..
As a result of these conditions it is normal for the valve bore to require reaming to the correct size to achive the correct valve stem to quide spec.
Also it is normal that the valve seat be cut to again maintain perfect alignment and resulting gas seal.
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April 6th, 2007, 11:48 AM   #6
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Originally Posted by Dr_C
Dear Mr toughie,
check that the end of the valve stem has no "burr". If so, gently grind the edge.
Mr. Toughie?? please explain?

Had that problem before and then followed Taffy's advice on grinding of the burr and they went straigth in, with the new guide it doesn't, so the burr is not the problem this time.
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April 6th, 2007, 11:50 AM   #7
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Originally Posted by nsman
As valve quides are a light press fit in the cylinder head and removing them requires thermal expansion and light force from a special tool the correct head to quide fit cannot be guaranteed as there is always the chance of metal stretching and transfer if an exact copy of the original guide is used as a replacement.As such it is normal for the guide to be slightly oversize to enable the correct interference fit.
As well the inner surface of the quide(where the valve slides)cannot be machined to fit the valve as the expansion of the quide inward from the press fit installation in the head makes this difficult calculate.
Also the installation of a new valve quide often results in the valve not being in the perfect original alignment with the valve seat..
As a result of these conditions it is normal for the valve bore to require reaming to the correct size to achive the correct valve stem to quide spec.
Also it is normal that the valve seat be cut to again maintain perfect alignment and resulting gas seal.
Thank you, that's what I needed to know, well it's off to the cylinder head specialist then I think.

Christof.
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April 7th, 2007, 01:30 AM   #8
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Originally Posted by BelgiqueBasterd
Originally Posted by Dr_C
Dear Mr toughie,
check that the end of the valve stem has no "burr". If so, gently grind the edge.
Mr. Toughie?? please explain?

Had that problem before and then followed Taffy's advice on grinding of the burr and they went straigth in, with the new guide it doesn't, so the burr is not the problem this time.
I tried to call you by your nick, but the B-word (in my spelling) was apparently censored automatically. The big brother watches you!

If no burr, then trust nsman. After fitting guides in the head, the hole usually gets somewhat smaller and needs reaming or honing.
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